Preparation and characterization of thermoplastic composite based on poly(vinylidene fluoride) and multiwalled carbon nanotube

We investigated the interrelationships among the crystal structures and the physical/ferroelectric/piezoelectric/rheological properties of a thermoplastic composite based on poly(vinylidene fluoride) (PVDF)/carbon nano tube (CNT). The composite was prepared by solution blending and the composite films were formed by hot-pressing. The contents of CNT were from 0.001 wt% to 3 wt%. To induce piezoelectric β-form crystal structure, the composite films were drawn by 400% elongation. The samples were poled at high voltage and high temperature for polarization of the film. The β-form crystal increased with CNT contents, passing through a peak, and decreased. The structural changes depended on the CNT contents, drawing and poling conditions. The maximum amount of β-crystal could be produced by optimum conditions in this study. The drawn and poled PVDF/CNT (0.2 wt%) composite film had the highest value of piezoelectricity. In the rheological properties, dynamic viscosity, the extent of shear thinning behaviors and relaxation time were increased with the CNT content.